| Title | Publisher | Year | Language | Documents |
|---|---|---|---|---|
| Of Their Shadows Deep | Amanda Walker | 2022 | English | Solution |
| Off-Season at the Dream Factory | B. J. Best | 2021 | English | Map, Solution |
| One Last Thing | Dee Cooke |
2020 | English | Map, Solution |
| Operation Extraction | Ming-Yee Iu | 2011 | English | |
| Opposite Edge of Slumber | Artem Flo | 2020 | English | Solution, Map |
| Our Boys in Uniform | Megan Stevens | 2013 | English | |
| Over Here! | Lionel Ange |
2020 | English | Map, Hints, Solution |